I did test with two scenarios.
In the first scenario, I did the installation and loaded the sample data, in this case I registered a new user account and a contact that has exchanged emails on imap, and the synchronization occurred correctly.

In the second scenario, I made an installation and not loaded the sample data, also registered the same user account and the same contact used of scenario 1, but the sync did not happen.

In the second scenario the log of job oro:cron:imap-sync shows that there has been success in connection to the imap server. It get the email,s but not stored in orocrm.

In the first scenario the log of job log oro:cron:imap-sync shows the same information but with a more detail. that some messages have been persisted, and it does not happen in the second scenario.

Is there some setting to be made to allow email sync on a clean installation?